Apparatus and methods for fabricating components

ABSTRACT

An additive manufacturing method for fabricating a component having a surface substantially free of imperfections may include providing a mold having a configuration corresponding to the component, and depositing a material on at least one surface of the mold to fabricate the component having the surface substantially free of imperfections.

TECHNICAL FIELD

Aspects of the present disclosure relate to apparatus and methods for fabricating components. In some instances, aspects of the present disclosure relate to apparatus and methods for fabricating components (such as, e.g., automobile parts, medical devices, machine components, consumer products, etc.) via additive manufacturing techniques or processes, which may be referred to as 3D printing manufacturing techniques or processes.

BACKGROUND

Additive manufacturing techniques and processes generally involve the buildup of one or more materials to make a net or near net shape (NNS) object, in contrast to subtractive manufacturing methods. Though “additive manufacturing” is an industry standard term (ASTM F2792), additive manufacturing encompasses various manufacturing and prototyping techniques known under a variety of names, including freeform fabrication, 3D printing, rapid prototyping/tooling, etc. Additive manufacturing techniques are capable of fabricating complex components from a wide variety of materials. Generally, a freestanding object can be fabricated from a computer-aided design (CAD) model.

A particular type of additive manufacturing, or 3D printing, technique and process generally includes forming and extruding a bead of flowable material (e.g., molten thermoplastic), applying such bead of material in a strata of layers to form a facsimile of an article, and machining such facsimile to produce an end product. Such a process is generally achieved by means of an extruder mounted on a computer numeric controlled (CNC) machine with controlled motion along at least the X, Y, and Z-axes. In some cases, the flowable material, such as, e.g., molten thermoplastic material, may be infused with a reinforcing material (e.g., strands of fiber) to enhance the material's strength. The flowable material, while generally hot and pliable, may be deposited upon a substrate (e.g., a mold), pressed down or otherwise flattened to some extent, and leveled to a consistent thickness, preferably by means of a tangentially compensated roller mechanism. The flattening process may aid in fusing a new layer of the flowable material to the previously deposited layer of the flowable material. In some instances, an oscillating plate may be used to flatten the bead of flowable material to a desired thickness, thus effecting fusion to the previously deposited layer of flowable material. The deposition process may be repeated so that each successive layer of flowable material is deposited upon an existing layer to build up and manufacture a desired component structure. When executed properly, the new layer of flowable material may be deposited at a temperature sufficient enough to allow new layer of flowable material to melt and fuse with a previously deposited layer of flowable material, thus producing a solid part.

While the aforementioned process achieves a near net shape much faster than depositing down a large number of very thin layers, a surface milling or other finishing operation is required to achieve the final net shape of the article, since it is deposited in stepped layers of tamped, extruded material. Such milling or finishing generally is accomplished using a rapidly spinning cutting tool with a round shaped tip, requiring numerous passes over the surface of the article, shifting over a small distance after each pass to generate the desired surface finish. In order to achieve a smooth surface, the amount the tool path is shifted after each pass must be relatively small; necessitating a large number of passes, which in turn requires considerable time to complete. While this approach may be satisfactory for a single item or a prototype part, it is less desirable for the production of multiple identical parts.

In view of the foregoing, the present disclosure provides systems and methods for producing articles from thermoplastic or flowable material using additive manufacturing techniques, which can generate multiple articles that are dimensionally accurate, and replicate the desired shape and surface features in less time, less effort, and reduced cost. Consequently, the present disclosure provides aspects of methods and apparatus for producing dimensionally accurate articles, which embody surface properties of sufficient quality, so as to negate the need for finishing operations.

SUMMARY

Aspects of the present disclosure relate to, among other things, methods and apparatus for fabricating components via additive manufacturing or 3D printing techniques. Each of the aspects disclosed herein may include one or more of the features described in connection with any of the other disclosed aspects.

In one embodiment, an additive manufacturing method for fabricating a component having a surface substantially free of imperfections may include providing a mold having a configuration corresponding to the component, and depositing a material on at least one surface of the mold to fabricate the component having the surface substantially free of imperfections.

Embodiments of the additive manufacturing method may include one or more of the following features: the at least one surface of the mold may define a cavity in the mold, and the at least one surface may include a concave or convex configuration; the at least one surface may be processed to resist adhesion of the material to the at least one surface; the surface substantially free of imperfections may be formed without a finishing step; the mold may be configured to control a cooling rate of the material deposited on the at least one surface of the mold; the step of depositing the material on the at least one surface of the mold may include extruding the material onto the at least one surface from a nozzle; the at least one surface may include a plurality of curves, and the nozzle may be configured for movement relative to the at least one surface such that a centerline of the nozzle remains perpendicular to a tangent plane for each curve of the plurality of curves; the nozzle may be configured to translate along a first axis, a second axis perpendicular to the first axis, and a third axis orthogonal to the first and second axes, and wherein the nozzle may be configured to rotate in a plane defined by the first and second axes; depositing the material on the at least one surface of the mold may include depositing a plurality of material beads adjacent to one another; the material may include a thermoplastic having a reinforcing material therein; the reinforcing material may include strands of fiber; depositing the material on the at least one surface of the mold may include fusing the material to an adjacent previously deposited bead of material; the nozzle may be part of a programmable computer numeric control (CNC) machine; and depositing the material on the at least one surface of the mold may include depositing the material in a pattern, wherein the pattern is based on a digital representation of the component.

In another embodiment, an additive manufacturing system for fabricating a component having a surface substantially free of imperfections may include a programmable computer numeric control (CNC) machine configured to extrude a flowable material. The additive manufacturing system may further include a mold having a cavity defining at least one surface for receiving a plurality of beads of the flowable material.

Embodiments of the additive manufacturing method may include one or more of the following features: the computer numeric control (CNC) machine may be configured to deposit the flowable material in a pattern based on a digital representation; the programmable computer numeric control (CNC) machine may include a nozzle for extruding the flowable material, and wherein the nozzle may be moveable along a first axis, a second axis perpendicular to the first axis, and a third axis orthogonal to the first and second axes, and wherein the nozzle may be configured to rotate in a plane defined by the first and second axes; the at least one surface may include a plurality of curves, and wherein the nozzle may be configured for movement relative to the at least one surface such that a centerline of the nozzle remains perpendicular to a tangent plane for each curve of the plurality of curves; the mold may include at least one heating element configured to control a rate of cooling of the flowable material; and the material may include a thermoplastic.

As used herein, the terms “comprises,” “comprising,” or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements, but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. The term “exemplary” is used in the sense of “example,” rather than “ideal.”

It may be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate exemplary aspects of the present disclosure and together with the description, serve to explain the principles of the disclosure.

FIG. 1 is a perspective view of an exemplary CNC machine operable pursuant to an additive manufacturing process in forming articles, according to an aspect of the present disclosure;

FIG. 2 is an enlarged perspective view of an exemplary carriage and applicator assembly of the exemplary CNC machine shown in FIG. 1;

FIG. 3 is an enlarged cross-sectional view of an exemplary material applicator head mounted on a lower end of the applicator assembly of FIG. 2, illustrating a bead of flowable material being extruded through an applicator nozzle onto a work surface, and a roller engaging and compressing a portion of such bead against such work surface, forming a ply of an article being manufactured, according to an aspect of the present disclosure;

FIG. 4 is a perspective view of an exemplary mold for fabricating components, according to an aspect of the present disclosure;

FIG. 5 is a perspective view of the mold of FIG. 4 partially covered with a layer of flowable material deposited therein and receiving an adjoining shaped bead of flowable material from a material applicator head of an exemplary CNC machine;

FIG. 6 is a side view of an application head, shown in a position wherein the centerline of the application head is perpendicular to the tangent plane of the contoured surface onto which the molten material is being deposited;

FIG. 7A is a perspective view of an exemplary completed component formed in the mold of FIG. 4, illustrating the application side of the component; and

FIG. 7B is another view of the FIG. 7A component, showing the inverse side of the component, the surface of which is replicated substantially without objectionable surface imperfections.

DETAILED DESCRIPTION

The present disclosure is drawn to, among other things, methods and apparatus for fabricating multiple components via additive manufacturing or 3D printing techniques. More particularly, the methods and apparatus described herein produce components having at least one surface substantially without (or free of) objectionable imperfections, thereby eliminating the need for additional finishing processes during manufacturing. Those of ordinary skill in the art will understand that a surface substantially without (or free of) objectionable imperfections may be a surface ready for use or delivery to a consumer without needing any further processing, such as, e.g., machining, sanding, grinding, etc., to, e.g., remove the imperfections.

In one aspect, fabrication of components having at least one surface substantially without objectionable imperfections is achieved by providing an open face mold of substantial and stable substructure, of a material that can tolerate a heated thermoplastic material, and upon which layers of flowable material may be deposited and thus stabilized. Such a mold would have one or more of a concave or convex surface that is the inverse of a surface of the article to be fabricated or otherwise replicated. In forming such an article, instead of depositing material in flat, horizontal layers as is traditionally done in the additive manufacturing process, material is deposited onto the surface of the open mold as the centerline of the application nozzle is maintained in substantially perpendicular alignment with the variable tangent plane of the contoured surface. Such a process requires the use of a CNC machine with controlled motion along the X, Y, and Z-axes, as well as an articulated application head with controlled rotational displacement about both the vertical and horizontal axes, essentially providing a flexible head at the output of the extruder through which the flowable material may be deposited upon a surface of the mold. After the flowable material has been deposited over the entire mold surface, and the material has cooled sufficiently to re-harden, the fabricated part can be removed. Since the surface of the part that was in contact with the mold has taken on the shape of the mold, which is the final shape desired, no further machining operations may be necessary.

Referring to FIG. 1 of the drawings, there is illustrated a programmable computer numeric control (CNC) machine 1 embodying aspects of the present disclosure. A controller (not shown) may be operatively connected to the machine 1 for displacing an application head along a longitudinal line of travel or an x-axis, a transverse line of travel or a y-axis, and a vertical line of travel or a z-axis, in accordance with a program inputted or loaded into the controller for performing an additive manufacturing process to replicate a desired component. CNC machine 1 may be configured to print or otherwise build 3D parts from digital representations of the 3D parts (e.g., AMF and STL format files) programmed into the controller. For example, in an extrusion-based additive manufacturing system, a 3D part may be printed from a digital representation of the 3D part in a layer-by-layer manner by extruding a flowable material. The flowable material may be extruded through an extrusion tip carried by a print head of the system, and is deposited as a sequence of beads on a substrate in an x-y plane. The extruded flowable material may fuse to previously deposited material, and may solidify upon a drop in temperature. The position of the print head relative to the substrate is then incremented along a z-axis (perpendicular to the x-y plane), and the process is then repeated to form a 3D part resembling the digital representation.

Machine 1 includes a bed 20 provided with a pair of transversely spaced side walls 21 and 22, a gantry 23 supported on side walls 21 and 22, carriage 24 mounted on gantry 23, a carrier 25 mounted on carriage 24, and an applicator assembly 26 mounted on carrier 25. Supported on bed 20 between side walls 21 and 22 is a worktable 27 provided with a support surface disposed in an x-y plane, which may be fixed or displaceable along an x-axis. In the displaceable version, the worktable may be displaceable along a set of rails mounted on the bed 20 by means of servomotors and rails 29 mounted on the bed 20 and operatively connected to the worktable 27. Gantry 23 is disposed along a y-axis, supported at the ends thereof on end walls 21 and 22, either fixedly or displaceably along an x-axis on a set of guide rails 28 and 29 provided on the upper ends of side walls 21 and 22. In the displaceable version, the gantry 23 may be displaceable by a set of servomotors mounted on the gantry 23 and operatively connected to tracks provided on the side walls 21 and 22 of the bed 20. Carriage 24 is supported on gantry 23 and is provided with a support member 30 mounted on and displaceable along one or more guide rails 31, 32 and 33 provided on the gantry 23. Carriage 24 may be displaceable along a y-axis on one or more guide rails 31, 32 and 33 by a servomotor mounted on the gantry 23 and operatively connected to support member 30. Carrier 25 is mounted on a set of spaced, vertically disposed guide rails 34 and 35 supported on the carriage 24 for displacement of the carrier 25 relative to the carriage 24 along a z-axis. Carrier 25 may be displaceable along the z-axis by a servomotor mounted on the carriage 24 and operatively connected to the carrier 25.

As best shown in FIG. 2, carrier 25 is provided with a base platform 36, a gear box 37 fixedly mounted on the upper side thereof, and a mounting platform 38 rotatably mounted on the underside of base platform 36. Platform 38 may be provided with openings therethrough disposed along the z-axis of the carrier 25. Gear box 37 may be provided with a gear arrangement having an opening therethrough and disposed coaxially with the aligned openings in gear box 37 and platforms 36 and 38, operatively connected to platform 38 for rotation about the z-axis and rotatable about such axis by means of a servomotor 39 mounted on base platform 36 and operatively connected to such gear arrangement.

Applicator assembly 26 may include an upper segment 41 and a lower segment 42. Upper segment 41 includes a transverse portion 41 a secured to the underside of mounting platform 38 for rotational movement about the z-axis. Upper segment 41 may be provided with an opening therethrough along such z-axis, and a depending portion 41 b may be disposed substantially laterally relative to such z-axis. Lower segment 42 includes a housing 42 b disposed on an inner side of depending portion 41 b. Housing 42 b may be mounted on a shaft journalled in a lower end of depending portion 41 b, intersecting and disposed perpendicular to the z-axis of carrier 25, and further housing 42 b may be provided with a laterally projecting application head 43 at a free end thereof. Mounted on a gearbox 44 provided on an outer side of segment portion 41 b is a servomotor 45 operatively connected through gearbox 44 to the shaft journalled in portion 41 b. Servomotor 45 may be configured for pivotally displacing lower segment 42 in a y-z plane. A material tamping roller 59 (shown in FIG. 3), rotatably mounted in carrier bracket 47, provides a means for flattening and leveling a bead of flowable material (e.g., molten thermoplastic), as shown in FIG. 3. Carrier bracket 47 may be adapted to be rotationally displaced by means of a servomotor 60 (shown in FIG. 2), through a sprocket 56 and drive-chain 65 arrangement.

With continuing reference to FIG. 3, application head 43 may include a housing 46 with a roller bearing 49 mounted therein. Carrier bracket 47 is fixedly mounted to an adaptor sleeve 50, journalled in bearing 49. As best shown in FIGS. 2-3, a conduit 52 consisting of an elongated, flexible material for conveying, e.g., a molten bead of a flowable material (e.g., molten thermoplastic) under pressure from a source disposed on carrier 25 or another source, to applicator head 43, may be fixedly (or removably) connected to, and in communication with nozzle 51. An intermediate portion of conduit 52 may be routed through the openings through gear box 37, support platform 36 and mounting platform 38, and along the z-axis of carrier 25. In use, the flowable material 53 (e.g., thermoplastic) may be heated sufficiently to form a molten bead thereof, which is then forced through conduit 52 and extruded through applicator nozzle 51, to form multiple rows of deposited material 53 in the form of molten beads, as described herein. Such beads of molten material 53 may be flattened, leveled, and/or fused to adjoining layers by any suitable means, such as, e.g., bead-shaping roller 59, to form an article. Even though bead-shaping roller 59 is depicted as being integral with applicator head 43, bead-shaping roller 50 may be separate and discrete from applicator head 43. In some embodiments, the deposited material 53 may be provided with a suitable reinforcing material, such as, e.g., fibers that facilitate and enhance the fusion of adjacent layers of extruded flowable material 53.

In some examples, machine 1 may include a velocimetry assembly (or multiple velocimetry assemblies) configured to determine flow rates (e.g., velocities and/or volumetric flow rates) of material 53 being delivered from applicator head 43. The velocimetry assembly preferably transmits signals relating to the determined flow rates to the aforementioned controller coupled to machine 1, which may then utilize the received information to compensate for variations in the material flow rates.

In the course of fabricating a component, pursuant to the methods described herein, the control system of the machine 1, in executing the inputted program, would operate the several servomotors as described to displace the gantry 23 along the x-axis, displace the carriage 24 along the y-axis, displace the carrier 25 along a z-axis, pivot lower applicator segment 42 about an axis disposed in an x-y plane and rotate bracket 47 about a z-axis thereof, in accordance with the inputted program, to provide the desired end product or a near duplicate thereof. A suitable mold (e.g., mold 62) is provided for depositing flowable material 53 thereon. Such a mold 62 may include at least one surface that is the inverse of the article to be produced, in essence, either a convex mold, or a concave mold, commonly referred to as a male mold or a female mold.

With reference now to FIG. 4, there is depicted an exemplary female mold 62, with a machined cavity, exemplary of a mold that may be used for forming, e.g. a vehicle engine-compartment lid. Mold 62 may be any suitable mold known in the art, including, but not limited to, molds formed by additive manufacturing or 3D printing processes. In some examples, mold 62 may include a solid body 63 and a cavity 64 formed therein. Cavity 64 may be formed by any suitable means known in the art, including, e.g., machining processes. One or more surfaces of cavity 64 maybe suitably prepared so as to prevent the adhesion of any molten thermoplastic material deposited thereon. For example, the one or more surfaces may be provided with a suitable coating and/or polished or otherwise finished so as to prevent molten thermoplastic from sticking to the one or more surfaces of cavity 64. In some embodiments, mold 62 may be configured to facilitate cooling or warming of material deposited thereon. For example, mold 62 may include one or more channels (not shown) disposed therein for circulation of cooled or heated fluid. The channels may be disposed in any suitable configuration to sufficiently heat or cool material (e.g., flowable material 53) deposited in cavity 64. In addition, or alternatively, mold 62 may be provided with one or more heating elements, such as, e.g., resistive heating elements, configured to warm mold 62 so as control a rate of cooling of material deposited in cavity 64.

Referring now to FIG. 5, with the machine suitably programmed and activated based on a selected profile relating to a part targeted for fabrication, beads of flowable material 53 may be extruded ahead of the path of roller 59, onto the machined or otherwise suitable prepared surface of cavity 64 of mold 62, accurately replicating the surface thereof and fusing laterally to adjoining, previously deposited beads, forming a single fused layer, thus forming an article that complements one or more surfaces of cavity 64. As best shown in the partial, sectioned view in FIG. 6, the engagement and compression of the bead by roller 59 compresses the bead of extruded material against the surface of said mold, as the application head 43 is pivoted to maintain substantial perpendicularity between the nozzle centerline and the tangent plane of the contoured surface of cavity 64 of mold 62. Stated differently, the application head may be rotated or otherwise displaced to remain perpendicular to a tangent plane of any curve (e.g., concave or convex) of the surface of cavity 64. The surface of an article thusly formed is an inverse duplication of the mold surface onto which it was deposited.

FIG. 7a exemplifies a vehicle engine-compartment lid 80, formed by the methods and apparatus described herein, as viewed from the deposition side 81, while FIG. 7b exemplifies the same item, as viewed from the finished side 82, replicated with substantially no objectionable surface imperfections. If necessary, only minimal machining or suitable finishing processes may be performed around the bottom periphery of such an item, in order to provide for a suitably finished mating surface.

While principles of the present disclosure are described herein with reference to illustrative embodiments for particular applications, it should be understood that the disclosure is not limited thereto. Those having ordinary skill in the art and access to the teachings provided herein will recognize additional modifications, applications, embodiments, and substitution of equivalents all fall within the scope of the embodiments described herein. Accordingly, the invention is not to be considered as limited by the foregoing description. 

We claim:
 1. An additive manufacturing method for fabricating a component having a surface substantially free of imperfections, the method comprising: providing a mold having a configuration corresponding to the component; and depositing a material on at least one surface of the mold to fabricate the component having the surface substantially free of imperfections.
 2. The additive manufacturing method of claim 1, wherein the at least one surface of the mold defines a cavity in the mold, and wherein the at least one surface includes a concave or convex configuration.
 3. The additive manufacturing method of claim 1, wherein the at least one surface is processed to resist adhesion of the material to the at least one surface.
 4. The additive manufacturing method of claim 1, wherein the surface substantially free of imperfections is formed without a finishing step.
 5. The additive manufacturing method of claim 1, wherein the mold is configured to control a cooling rate of the material deposited on the at least one surface of the mold.
 6. The additive manufacturing method of claim 1, wherein the step of depositing the material on the at least one surface of the mold includes extruding the material onto the at least one surface from a nozzle.
 7. The additive manufacturing method of claim 6, wherein the at least one surface includes a plurality of curves, and wherein the nozzle is configured for movement relative to the at least one surface such that a centerline of the nozzle remains perpendicular to a tangent plane for each curve of the plurality of curves.
 8. The additive manufacturing method of claim 6, wherein the nozzle is configured to translate along a first axis, a second axis perpendicular to the first axis, and a third axis orthogonal to the first and second axes, and wherein the nozzle is configured to rotate in a plane defined by the first and second axes.
 9. The additive manufacturing method of claim 1, wherein depositing the material on the at least one surface of the mold includes depositing a plurality of material beads adjacent to one another.
 10. The additive manufacturing method of claim 1, wherein the material includes a thermoplastic having a reinforcing material therein.
 11. The additive manufacturing method of claim 1, wherein the reinforcing material includes strands of fiber.
 12. The additive manufacturing method of claim 1, wherein depositing the material on the at least one surface of the mold includes fusing the material to an adjacent previously deposited bead of material.
 13. The additive manufacturing method of claim 6, wherein the nozzle is part of a programmable computer numeric control (CNC) machine.
 14. The additive manufacturing method of claim 1, wherein depositing the material on the at least one surface of the mold includes depositing the material in a pattern, wherein the pattern is based on a digital representation of the component.
 15. An additive manufacturing system for fabricating a component having a surface substantially free of imperfections, comprising: a programmable computer numeric control (CNC) machine configured to extrude a flowable material; and a mold having a cavity defining at least one surface for receiving a plurality of beads of the flowable material.
 16. The additive manufacturing system of claim 15, wherein the computer numeric control (CNC) machine is configured to deposit the flowable material in a pattern based on a digital representation.
 17. The additive manufacturing system of claim 15, wherein the programmable computer numeric control (CNC) machine includes a nozzle for extruding the flowable material, and wherein the nozzle is moveable along a first axis, a second axis perpendicular to the first axis, and a third axis orthogonal to the first and second axes, and wherein the nozzle is configured to rotate in a plane defined by the first and second axes.
 18. The additive manufacturing system of claim 17, wherein the at least one surface includes a plurality of curves, and wherein the nozzle is configured for movement relative to the at least one surface such that a centerline of the nozzle remains perpendicular to a tangent plane for each curve of the plurality of curves.
 19. The additive manufacturing system of claim 15, wherein the mold includes at least one heating element configured to control a rate of cooling of the flowable material.
 20. The additive manufacturing system of claim 15, wherein the material includes a thermoplastic. 